In the field of poultry processing, it is generally known to use a rotary mandrel (i.e., a bore or probe) conveyed through the belly cavity of the bird and into the neck opening of the bird for the removal of the gullet, crop, windpipe, etc. Such a device is known from published European Patent Application EP-Al-0,162,154, in which a so-called "decropper" is used in mechanized and automated slaughtered systems for poultry. After evisceration, parts of the gullet, windpipe, crop and any adhering parts can be left behind in the neck region of the poultry, and must be removed for hygienic and marketing reasons.
This removal can be carried out with the decropper which is known per se. It is important here first of all that the removal should take place with great certainty. Insufficiently decropped birds have to be returned to the decropper again after inspection. This leads to a lower capacity of the slaughter system, or to higher slaughter costs for the same capacity.
Secondly, it is important that the decropping takes place in such a way that the poultry is not damaged. This could involve damage to or breakage of bones of the poultry and damage to meat or skin of the poultry.
Thirdly, partly in view of the trend towards a high degree of automation in slaughter systems, it is increasingly important that the operations carried out on the poultry are carried on in such a way that as much meat as possible becomes available as an end product.
In order to meet the first requirement, the mandrel of the above-described decropper (EP-Al-0,162,154) must have a certain minimum diameter, so that when the mandrel is inserted into the neck opening the neck is stretched somewhat. This decropper will therefore not be able to meet the second and third requirements because the forces exerted by the mandrel on the neck opening can lead to damage of bone and/or meat.
Other decroppers are also known per se, such as the decropper according to U.S. Pat. No, 4,208,764. The latter generally cannot meet the second and third requirements because the mandrel used is provided with angular, radially directed projections. Moreover, the neck region is pulled additionally against these angular parts, due to the vacuum used.
The decropper known from Dutch Patent Application NL-A-8303633 generally cannot meet the second and third requirements because the mandrel used therein is provided at its end with forward-pointing projections which are of such a shape that there is a great risk of damage to bones and meat through the action of the pointed projections thereon. Similar disadvantages are demonstrable for the decropper according to European Patent No. EP-Bl-0,178,825.
From European Patent No. EP-Bl-0,204,366 a decropper is known which does meet the three requirements through the fact that the actual working mandrel thereof is partially enclosed by a non-rotating smooth cylinder moving with the mandrel in the axial direction. This decropper is however, mechanically more complex than a decropper with only a mandrel.
Finally, reference is made to a decropper from Dutch Patent Application NL 8801707, which meets the second and third requirements by avoiding the use of pointed and angular parts in the mandrel. However, the first requirement is met only to a lesser extent.
Accordingly, it can be seen that a need yet remains for a method and apparatus for decropping poultry which is effective for reliably decropping poultry with certainty, avoids or minimizes damage to skin, meat, and bones, and results in an efficient recovery of meat with minimal waste. It is to the provision of such a method and apparatus that the present invention is primarily directed.